Travancore lines

Nedumkotta or Travancore lines was a wall built as a protection against consistent invasion and threats from northern kingdoms mainly Zamorins of Kozhikode. It was built by the Dharma Raja Karthika Thirunal (d.A D 1764), King of Travancore with the request,support and permission of the Kingdom of Kochi.

The Nedumkotta was a defence fortification constructed along the northern borders of the erstwhile Travancore allied Cochin State.of 1757-1762AD.The places north of Nedumkotta was under Zamorin occupied Cochin.(1757-1762)It passed through the territories of the then Cochin State.

The Nedumkotta was built primarily to resist the invasion under Hyder Ali Khan against Travancore State and southern parts Cochin state.. It was raised mainly with clay and mud, and reinforced with stones, laterite and granite at strategic places. It started from the KrishanKotta on the west coast, above Kodungallur, and stretched up to the Annamalai Hills on the Western Ghats. It was about 48 km long, 20 feet wide and 12 feet high. Its alignment was along the Periyar river on the west coast up to Chalakudy from where it went along the Chalakudy river up to the Annamalai Hills in the east. There were underground cells to store gunpowder and other war materials, special chambers for soldiers to live, and look-outs and mounted field-guns all along the fortification. Besides, on the north side of the fortification, ditches were dug twenty feet wide and sixteen feet deep, and filled with thorny plants, poisonous snakes, and hidden weapons. On the south side as well as on the top of the fortification, wide roads were laid for the convenience of military movements.

The fortification was constructed during the regime of Rama Varma Raja, popularly known as Dharma Raja of Travancore, and under the direct guidance and supervision of the then Prime Minister, Ayyappan Marthanda Pillai, and the then Commander of the Travancore Army, the Dutch Captain D'Lenoy. This historic defence line was comparable to the Great Wall of China except that the latter was more ancient and greater in length. It was under the protective cover of this Nedumkotta that a small army of Travancoreans under the command of Raja Keshavadas defeated and frustrated near Alwaye a formidable army led by Tipu Sultan.

...
Wikipedia